Packet transmission device, packet transmission method, and storage medium

Abstract

A packet transmission device transmits data packets to a packet receiving device using a first communication link and a second communication link with a smaller communication area than the first communication link. The device determines the communication status of the second communication link, sets either one of the first or second communication link as a main communication link and the other as a sub communication link, based on the determination results, generates instructions to transmit main data packets on the main communication link and sub data packets with bandwidth limitation on the sub communication link, transmit the main data packets or the sub data packets via the first communication link based on the instructions, and transmits the sub data packets or the main data packets via the second communication link based on the instructions.

What is claimed is: 
     
         1 . A packet transmission device that transmits data packets to a packet receiving device using a first communication link and a second communication link that has a smaller communication area than the first communication link, the device comprising:
 a packet storage that stores the data packets;   a communication status determination unit that determines the communication status of the second communication link;   a main and sub link setting unit that sets either one of the first or second communication link as the main communication link and the other as the sub communication link, based on the determination results;   a packet generation unit that generates, from the data packets, main data packets without bandwidth limitation and sub data packets with bandwidth limitation;   a transmission instruction unit that instructs each of a first communication unit and a second communication unit to transmit the main data packets on the main communication link or transmit the sub data packets on the sub communication link;   the first communication unit that transmits the main data packets or the sub data packets via the first communication link based on the instruction from the transmission instruction unit;   the second communication unit that transmits the sub data packets or the main data packets via the second communication link based on the instruction from the transmission instruction unit.   
     
     
         2 . The packet transmission device according to  claim 1 , wherein,
 the communication status determination unit determines the communication status of the second communication link based on a reception condition of a confirmation response sent by the packet receiving device that received the main data packets or the sub data packets.   
     
     
         3 . The packet transmission device according to  claim 2 , wherein,
 the communication status determination unit determines that the communication status of the second communication link is poor in a case that no confirmation response has been received before a predetermined time elapses after the main data packets are sent over the second communication link.   
     
     
         4 . The packet transmission device according to  claim 1 , wherein,
 the bandwidth limitation is policing to thin out the data packets on a packet-by-packet basis.   
     
     
         5 . The packet transmission device according to  claim 4 , wherein,
 when the second communication link is the sub communication link, the packet generation unit performs the policing by increasing the degree of thinning compared to when the first communication link is the sub communication link.   
     
     
         6 . The packet transmission device according to  claim 3 , wherein,
 when the communication status determination unit determines that the communication status of the second communication link is poor, the transmission instruction unit instructs the first communication unit to transmit the data packets transmitted by the second communication unit for which the corresponding acknowledgement has not been received.   
     
     
         7 . The packet transmission device according to  claim 3 , wherein,
 when the communication status determination unit determines that the communication status of the second communication link is poor, the transmission instruction unit instructs the first communication unit to transmit the data packets that have been transmitted by the second communication unit, for which the corresponding confirmation response has not been received and which have not been transmitted by the first communication unit in the past.   
     
     
         8 . The packet transmission device according to  claim 1 , which is mounted to a mobile object. 
     
     
         9 . A packet transmission method using a packet transmission device that transmits data packets to a packet receiving device using a first communication link and a second communication link that has a smaller communication area than the first communication link, the method comprising:
 determining the communication status of the second communication link;   setting either one of the first or second communication link as the main communication link and the other as the sub communication link, based on the determination results;   generating main data packets without bandwidth limitation and sub data packets with bandwidth limitation from the data packets stored in the packet storage;   generating instructions to transmit the main data packets on the main communication link and the sub data packets on the sub communication link;   transmitting the main data packets or the sub data packets via the first communication link based on the instructions;   transmitting the sub data packets or the main data packets via the second communication link based on the instructions.   
     
     
         10 . A computer-readable non-transitory storage medium storing a packet transmission program, the program causing a packet transmitting device that transmits data packets to a packet receiving device using a first communication link and a second communication link that has a smaller communication area than the first communication link to:
 determine the communication status of the second communication link;   set either one of the first or second communication link as the main communication link and the other as the sub communication link, based on the determination results;   generate main data packets without bandwidth limitation and sub data packets with bandwidth limitation from the data packets stored in the packet storage;   generate instructions to transmit the main data packets on the main communication link and the sub data packets on the sub communication link;   transmit the main data packets or the sub data packets via the first communication link based on the instructions;   transmit the sub data packets or the main data packets via the second communication link based on the instructions.